It is well known that the conventional textile tire reinforcements are two or three-ply cords having closed plies, which means, each individual ply has interface contact with each other. Such textile cords, for example, can be rayon, polyester, nylon and aramid/nylon hybrid cords in pneumatic radial and bias tires.
The aramid/nylon hybrid cords having bi-elasic tensile properties comprising high modulus aramid and low modulus nylon yarns have improved bending fatigue resistance compared to the aramid cord with comparable constructional parameters like total dtex, and twist multiplier. The cushion effect of the low modulus nylon (less abrasion between the cord plies) improves the fatigue resistance of aramid/nylon hybrid cords.
U.S. Pat. No. 4,155,394 describes a composite (hybrid) cord suitable for tire reinforcement comprised of a plurality of plies of yarns selectively cabled in a manner so that, upon application of longitudinal stress, at the initial elongation of the cable, the primary load bearing ply is a polyester or a nylon yarn and so that after appreciable elongation of the cable, the primary load bearing yarn is an aramid yarn. The invention further relates to a pneumatic tire, industrial belt or hose having a carcass containing a fabric of such a cord as a reinforcing member.
U.S. Pat. No. 7,484,545 describes heavy dtex hybrid cords having high modulus aramid and low modulus nylon as carcass and crown reinforcement in radial aircraft tires. The breaking strength of such hybrid cords are higher than 1050N and elongation at break values are higher than 12 and less than 20%.
US Patent No. 2014/0360648 describes a carcass cord consisting of one single aramid first yarn twisted helically about one single polyester second yarn. The first yarn and second yarn have different moduli of elasticity. The first yarn has a modulus greater than the modulus of the second yarn.